The present invention relates to a microbicidal composition and to its use for preserving technical products.
Preservatives are used in many aqueous systems in order to control microbial growth. An important field of use of chemical preservatives is in technical products such as water-mixed cooling lubricants, fuels, paints and coatings. For example, their use in diesel fuels is necessary because microorganisms can multiply therein, particularly when water of condensation settles to the bottom or is present in finely dispersed form within the fuels. If microbial growth is not suppressed it leads to sludge formation (biomass) and to corrosion by metabolic products of the microorganisms (biocorrosion).
It has been known for a relatively long time to use formaldehyde donor compounds as biocides in technical products since they not only have an effect against bacteria, but also against yeasts and moulds. Such formaldehyde donor compounds include, inter alia, O-formals and N-formals.
DE 199 61 621 A1 discloses a stable microbicidal composition for technical products which comprises at least one bactericidal N-formal, at least one fungicide and at least one stabilizer, e.g. 2-mercaptopyridine N-oxide, and corresponding salts.
DE 198 42 116 A1 discloses the use of methylenebisoxazolidine derivatives for increasing the solubility of derivatives of 1H-benzimidazol-2-ylcarbamic acid in liquid preparations or preservatives for use in technical products. The compositions described therein can comprise further active ingredients, in particular N-formals and/or O-formals, additives and/or auxiliaries, e.g. stabilizers.
Further microbicidal compositions which comprise formaldehyde donor compounds as active ingredient are known from U.S. Pat. No. 4,655,815, GB 2 274 779 A, EP 0 327 220 B1, DE 41 41 953 A1, U.S. Pat. Nos. 5,428,050, 5,496,842, DE 197 05 085 A1, DE 197 22 858 A1 and DE 101 22 380 A1.
Furthermore, there are numerous commercially available preservatives based on N-formals and/or O-formals.
One example of the use of N-formals in a commercial product is the reaction product of formaldehyde or paraformaldehyde and ethanolamine (Grotan BK=N,N′,N″-tris(hydroxyethyl)hexahydrotriazine), which has been used successfully for years as preservative in the cooling lubricant sector.
A further preservative for technical products, in particular for the cooling lubricant sector is Grotan WS, a 1:1 condensation product of p-formaldehyde and isopropanolamine (N,N′,N″-tris(β-hydroxypropyl)hexahydrotriazine).
For many years use has also been made of a condensation product of p-formaldehyde and isopropanolamine (weight ratio 3:2, Mar 71 or Grotan OX or GrotaMar 71=N,N′-methylenebis(5-methyloxazolidine) in technical products.
During the storage and the transportation of packs containing formaldehyde donor preparations, the problem often arises that the container loses dimensional stability as the storage time continues and can have a so-called “neck-in”. The term “neck-in effect” is understood as meaning the permanent deformation of a container, such as an indentation of the material, shrinkage, deformation of the container ranging to severe deformation or deviation from the dimensional stability. For example, in the case of packs containing Grotan OX, a neck-in effect arises after about 14 days, and at elevated storage temperatures after just 7 to 14 days. For other preparations, such as combinations of Grotan® OX with urea (e.g. Grotan® OF) or fungicides (e.g. Grotan® OD), the onset of the neck-in effect may also arise after a delay, e.g. after 2 to 6 months at ambient temperature. System cleaners such as Grotanol SR 1 may also possibly exhibit a neck-in following storage.
Since the neck-in effect impairs the stackability of packs, the risk of accident during their handling, storage and transportation is increased, which overall reduces the acceptance by the consumer or customer. Moreover, a final product which, under transportation conditions (e.g. sea transportation in tropical countries), has a tendency toward deformation of the packaging material and thus represents a safety problem, may require higher insurance premiums. A product not packaged in accordance with requirements is also associated with a reduction in value.
In order to reduce the neck-in effect, it is possible, for example, to use packs with comparatively high wall strengths or more resistant packaging materials. However, this leads to an increase in the costs as a result of the greater material use and expenditure in choosing suitable packagings.
Recently, preservatives, e.g. Grotan® OF, have come onto the market which comprise emission-reducing additives, e.g. urea and urea derivatives, in addition to N-formals. By adding such emission-reducing additives it was possible not only to reduce the emission of the readily volatile formaldehyde from these products, but also to achieve advances in reducing the neck-in effect of formulated products.
However, for some applications, a significant increase in the solids content in the formaldehyde donor preparation as a consequence of incorporating further additives is undesired. For example, in the case of the use of formaldehyde donor preparations as fuel additive, it may lead to the blockage of injection nozzles or deposits in the engine compartment, when, for example, amounts of urea with an emission-reducing effect are used in addition to microbicidal active ingredients.
There thus continues to be a need for preservatives based on formaldehyde donor compounds which contribute, in the form of the formulated product, to a reduction in the neck-in effect on the packs used for storage and for transportation.